 The photograph on the left shows a typical habitat of brown long-eared bats.

Roost Sites and Patterns

Summer roost: Nursery roosts are found from May (Swift, 1991a) and usually consist of 10-30 individuals, although recordings of up to 200 individuals have been made (Greenaway & Hutson, 1990). Males are often present in nurseries. Roost in roofs of buildings either singly, in crevices and timber, or in clusters around chimneys and ridge ends.

Winter roosts: Hibernate from November through to late March (Swift, 1991a). Roost in cooler regions of caves and similar environments. Brown long-eared bats are usually found in crevices but may be on the wall, sometimes hanging freely with the wings partially wrapped around the body. Usually roost singly or in very small clusters although they may roost with other bat species.

Often found in bat boxes. May also occupy bird boxes and tree holes.

Brown long-eared bats appear to select roosting sites according to the houses available. Preferences for older buildings with partitioned roofs which are within 0.5 km of woodland and water have been recorded. Brown long-eared bats also exhibit a preference for warmer houses for summer roost sites (Entwistle et al., 1997). Given that loss of roost sites is a major threat to British bats, this information should be considered when implementing conservation programs.

Usually only emerge in the dark, around an hour after sunset (Russ, 1999). May be active and make short flights within the roost prior to emergence. Return after 1-2 hours if suckling infants, if not return at dawn (Swift, 1991a).

Flight is slow, fluttering and low, generally close to vegetation. Often includes sweeping glides and hovering.

Flight is very agile, even in very confined areas.

The wings of juvenile brown long-eared bats grow faster than their body mass, altering their wing loading and hence their flying ability as they develop. At an age of 30 days juveniles have become more manoeuvrable and can fly more slowly at minimum power due to this allometric growth. This coincides with the time at which brown long-eared bats first leave their roost (McLean & Speakman, 2000).

Forages close to the roost in open woodland or parkland. Brown long-eared bats display a preference for deciduous woodland, and can glean insects from various surfaces (Entwistle et al., 1996).

Forages about 5-6m above the ground where there is thick vegetation (Swift, 1991a).

Foraging flight has short, twisting sections and includes upward scanning of vegetation.

The diet of brown long-eared bats consists almost exclusively of Lepidoptera, including many tympanate species (Vaughan, 1997).

A study by Sheil et al. (1991) on a population of brown long-eared bats in western Ireland showed that 42% of their diet was made up of insects which were probably gleaned from various surfaces such as foliage and the ground. The prey are thought to have been gleaned because they were insects that were diurnal or rarely flew, or non-flying arthropods. Ground-dwelling prey such as centipedes and the dipteran muscid Scatophaga stercoraria appeared to be common dietary components. The majority of prey items consumed by the brown long-eared bats were Diptera and Lepidoptera. Evidence of some very small prey items, such as aphids, was also found.

Large prey items are often consumed at a night perch.

Feeding sites are used and may be shared with individuals from the same roost (Entwistle et al., 1996).

Prey is probably detected by sight and sound using the large eyes and ears, not by echolocation. A study by Eklöf and Jones (2003) demonstrated the ability of the brown long-eared bat to visually detect prey. Under experimental conditions, brown long-eared bats showed a preference for situations where sonar and visual cues were available. However, visual cues were more important that sonar cues and the bats were unable to detect prey items using only sonar cues. Brown long-eared bats have relatively large eyes and ears and it is likely that visual information and passive listening allow this species to detect prey in cluttered environments.

Marked in blue on the diagram above is a typical foraging path of brown long-eared bats (based on Russ, 1999).